CN116157710A

CN116157710A - Dynamic mirror for a vehicle

Info

Publication number: CN116157710A
Application number: CN202180055511.1A
Authority: CN
Inventors: J·R·萨尔根特; R·J·吉布森; J·G·芬登; N·R·布兰达; G·斯图尔特; J·D·斯尼尔; M·N·罗伯茨
Original assignee: Shounuo Canada
Current assignee: Shounuo Canada
Priority date: 2020-07-15
Filing date: 2021-07-13
Publication date: 2023-05-23
Also published as: US20230244117A1; EP4182755A1; KR20230037650A; US20230251406A1; EP4182756A1; WO2022011462A1; WO2022011463A1; JP2023535873A; KR20230125337A; JP2023535872A; CN116056950A

Abstract

A dynamic mirror assembly is disclosed that can vary the amount of reflected light, the dynamic mirror assembly including a mirror and a switching material. The switching material is placed between the mirror and the observer and has a dark state and a bright state and switches state in at least one direction due to a photochromic reaction and switches in the other direction due to one or more of a photochromic reaction or an electrochromic reaction or a thermal reversal above a threshold temperature.

Description

Dynamic mirror for a vehicle

RELATED APPLICATIONS

The present application claims priority to U.S. provisional patent application U.S.63/039,426 filed on 7/15/2020, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates generally to mirrors used in transportation, such as side or rear view mirrors for vehicles. The article is more specifically designed to lighten or darken using photochromic or hybrid photochromic/electrochromic or thermal inversion techniques.

Background

A key safety aspect in automotive operation is the ability of the rear and side view mirrors to enhance the field of view of the vehicle operator. This ability can be significantly impaired when glare is introduced, the term glare being used herein as a characteristic caused by sunlight during the day or the headlights of another vehicle at night. Glare can cause difficulties in seeing in mirrors due to direct or reflected sunlight or glare from the headlights of other vehicles, and glare is caused by the significant difference in light from what is being observed (e.g., other vehicles) and the glare source.

Many automotive mirrors employ some type of anti-glare technology in order to improve visibility. Older mirrors employ mechanical techniques that adjust the mirror angle so that the amount of reflected light is greatly reduced. Materials that dynamically adjust the amount of light passing therethrough may also be used to make the rearview mirror. Electrochromic mirrors (such as those manufactured by Gentex Corporation of Zeeland, MI) are well known in the art (e.g., patent No. US 4443057).

Another example of using dynamic filters to handle glare is the use of photochromic materials. US5373392 describes a "photochromic light control mirror" in which a photochromic material similar to that used in spectacles (e.g. US5274132 and US 5369158) is darkened using a fluorescent UV light source. As with eyewear technology, these photochromic switching materials rely on a thermal reverse reaction to drive the transition back to the lit state. During the normal operating temperature of the mirror, a thermal reverse reaction occurs naturally. However, the rate of thermal reverse reaction and the extent of reaction are affected by the temperature experienced by the mirror. The dark state achieved and the switching rate of this existing photochromic technique therefore depend to a large extent on the temperature. At colder temperatures, the photostable of the photochromic medium will shift so that the mirror will become darker due to slower thermal reverse reactions, possibly too dark to be used effectively. Conversely, at warmer temperatures, the photostable of the photochromic medium will shift such that the mirror becomes less dark due to the faster thermal reverse reaction, and may be too bright to be used effectively, i.e., a shortcoming that would be apparent in the low reflectance state or night mode.

Another problem arises in that some of these techniques are controlled by a continuous light source, as in US20050270614 A1. In other words, a light source emitting a specific wavelength needs to be continuously turned on to darken the photochromic material and keep it in darkness, thereby increasing the total power consumption. The resulting problem then also arises in dissipating the heat generated from the continuous light source, as this heat will increase the degradation rate and further alter the photostability of the photochromic material.

Disclosure of Invention

In another aspect, the invention relates to a dynamic mirror assembly that can vary the amount of reflected light. According to the invention, the dynamic mirror comprises a mirror; and a switching material disposed between the mirror and the viewer, having a dark state and a light state, the switching material switching state in at least one direction due to a photochromic reaction and the switching material switching in the other direction due to one or more of a photochromic reaction or an electrochromic reaction or a thermal inversion above a threshold temperature.

Other aspects of the invention are as disclosed and claimed herein.

Drawings

These and other features will become more apparent from the following description with reference to the accompanying drawings. The drawings are for illustrative purposes and may not show relative proportions or proportions unless otherwise indicated.

FIG. 1 shows an exploded view of a mirror according to one example.

Fig. 2 shows an exploded view of a mirror according to another example.

Fig. 3 shows an exploded view of a mirror according to another example.

Fig. 4 shows an exploded view of a mirror according to another example.

Fig. 5 shows a schematic view of a mirror according to another example.

Fig. 6a, 6b, 6c and 6d show an embodiment of a prototype mirror according to another example.

Fig. 7 shows a schematic diagram of a simple circuit for powering LEDs for dimming and brightening mirrors.

Fig. 8 illustrates one embodiment of an LED circuit on a circuit board.

Fig. 9a, 9b, 9c and 9d show LED arrangements according to different embodiments.

Fig. 10 shows a general circuit for dimming and brightening LEDs.

Detailed Description

The present invention relates in various aspects to dynamic mirrors with variable reflectivity, such as rear and side view mirrors for vehicles (and particularly automobiles). That is, the amount of light reflected by the mirror may vary depending on the situation, for example, to reduce glare from headlights on rear vehicles at night. The mirror may comprise a switching material comprising, for example, a selectively brightable or darkenable photochromic or photochromic/electrochromic material whereby the mirror is caused to reflect more or less light by user control or by an automated system based on time and/or geographic location and/or sensor input.

The invention then relates in one aspect to a dynamic mirror assembly that can vary the amount of reflected light, comprising a mirror and a switching material. The switching material is placed between the mirror and the viewer, has a dark state and a bright state, and switches states in at least one direction due to a photochromic reaction and switches in the other direction due to one or more of a photochromic reaction or an electrochromic reaction.

In one aspect, the mirror has high reflectivity in the visible region and high transmissivity in the ultraviolet region. In one aspect, the mirrors may be mutual mirrors that appear reflective on one side and transparent on the other side.

In one aspect, the switching material includes a chromophore that switches state in at least one direction due to a photochromic reaction and that switches in another direction due to one or more of a photochromic reaction or an electrochromic reaction.

In another aspect, the switching material may also include a polymer, such as polyvinyl butyral. In yet another aspect, the mirror may comprise one or more of gold, chromium, aluminum, or silver sputtered onto the transparent substrate.

In a further aspect, the mirror may include a multilayer dielectric material having alternating layers of high refractive index material and low refractive index material.

In yet another aspect, the chromophore used may switch to the dark state via a photochromic reaction when excited by light of one wavelength range, and the chromophore used may switch to the bright state via a photochromic reaction when excited by light of a different wavelength range.

In a further aspect, the dynamic mirror assembly of the present invention may further comprise a light emitting diode on the opposite side of the mirror from the switching material, the light emitting diode emitting light in a fixed wavelength range to drive one of the state changes. In yet another aspect, the light emitting diode may drive the switching material from the bright state to the dark state. In a further aspect, a fixed wavelength light emitting diode having a wavelength of about 350nm to about 410nm and used to dim the switching material may be used. In yet another aspect, the dynamic mirror assembly may include an additional light emitting diode that emits light in a wavelength range of 450nm to 800m to lighten the switching material.

According to the present invention, the dynamic mirror assembly may further comprise a filter between the switching material and sunlight, such that filtered sunlight transitions the switching material from the dark state to the bright state.

In another aspect, the switching material may comprise a photochromic-electrochromic material, and the switching material may darken in response to light and lighten in response to electricity. In yet another aspect, the switching material may comprise a photochromic-electrochromic material, and the switching material may darken in response to light and lighten in response to electricity. According to aspects of the present invention, the photochromic-electrochromic material may include one or more chromophores.

In other aspects, the switching material may be a photochromic or photochromic-electrochromic switching material, and may include a P-type photochromic material.

In one aspect of the dynamic mirror assembly of the present invention, the dark state of the switching material does not spontaneously revert to the bright state upon removal of the light source in the temperature range of-20 ℃ to 50 ℃, or in the temperature range of-30 ℃ to 60 ℃, or in the temperature range of-40 ℃ to 70 ℃. In another aspect, the dynamic mirror assembly has a daytime mode and a nighttime mode, and the mirror assembly is in a high reflectivity state during the daytime mode and in a low reflectivity state during the nighttime mode.

In one aspect, the dynamic mirror assembly of the present invention may include a controller that controls whether the mirror should be in daytime or nighttime mode based on one or more of a clock, light sensor, or GPS signal. In another aspect, the dynamic mirror assembly of the present invention may further comprise a controller capable of automatically placing the mirror in an intermediate state between the dark state and the light state according to manual input or based on one or more of a clock, a light sensor, or a GPS signal.

In another aspect, the present invention is directed to a dynamic mirror assembly that can vary the amount of reflected light, including a mirror and a switching material. The switching material is placed between the mirror and the viewer, has a dark state and a bright state, and switches states in at least one direction due to a photochromic reaction, and switches in the other direction due to one or more of a photochromic reaction or an electrochromic reaction or a thermal reversal above a threshold temperature.

In aspects, the switching material switches in the other direction due to the photochromic reaction only, the electrochromic reaction only, or both the photochromic reaction and the electrochromic reaction.

In another aspect, the switching material switches in the other direction only due to the thermal inversion above a threshold temperature.

In one aspect, the mirror has high reflectivity in the visible region and high transmissivity in the ultraviolet region.

In another aspect, the mirrors are mutual mirrors that appear reflective on one side and transparent on the other side.

In another aspect, the switching material includes a chromophore that switches state in at least one direction due to a photochromic reaction and that switches in another direction due to one or more of a photochromic reaction or an electrochromic reaction or thermal inversion above a threshold temperature.

In one aspect, the switching material further comprises polyvinyl butyral.

In one aspect, the mirror may comprise one or more of gold, chromium, aluminum, or silver sputtered onto a transparent substrate. In another aspect, the mirror can include a multilayer dielectric material having alternating layers of high refractive index material and low refractive index material.

In one aspect, the chromophore switches to the dark state via a photochromic reaction when excited by light of one wavelength range, and the chromophore switches to the bright state via a photochromic reaction when excited by light of a different wavelength range.

According to the invention, the dynamic mirror assembly may further comprise a light emitting diode on the opposite side of the mirror from the switching material, the light emitting diode emitting light in a fixed wavelength range to drive one of the state changes. In an aspect, the light emitting diode may drive the switching material from the bright state to the dark state. In another aspect, the fixed wavelength is from about 350nm to about 410nm and is used to darken the switching material.

In one aspect, the dynamic mirror assembly of the present invention may further include an additional light emitting diode that emits light in a wavelength range of 450nm to 800m to lighten the switching material. In another aspect, the dynamic mirror assembly of the present invention may further comprise a filter between the switching material and sunlight such that filtered sunlight transitions the switching material from the dark state to the bright state.

In one aspect, the switching material comprises a photochromic-electrochromic material, and the switching material darkens in response to sunlight and lightens in response to electricity. In another aspect, the switching material comprises a photochromic-electrochromic material, and the switching material darkens in response to light and lightens in response to electricity. In yet another aspect, the switching material comprises a P-type photochromic material.

In yet another aspect, the switching material may include a photochromic material that photochromically switches to the light state and switches to the dark state due to thermal reversals above the threshold temperature. In a further aspect, the switching material comprises a photochromic material that photochromically switches to the dark state and switches to the light state due to thermal reversals above the threshold temperature.

In various aspects, the threshold temperature useful according to the present invention is at least 50 ℃, or at least 60 ℃, or at least 70 ℃.

In one aspect, the dark state of the switching material does not spontaneously revert to the bright state upon removal of the light source in a temperature range of-20 ℃ to 50 ℃, or in a temperature range of-30 ℃ to 60 ℃, or in a temperature range of-40 ℃ to 70 ℃.

In one aspect, the dynamic mirror assembly of the present invention has a daytime mode and a nighttime mode, and the dynamic mirror assembly is in a high reflectivity state during the daytime mode and in a low reflectivity state during the nighttime mode.

In one aspect, the dynamic mirror assembly of the present invention includes a controller that controls whether the dynamic mirror assembly should be in daytime or nighttime mode based on one or more of a clock, light sensor, or GPS signal. In another aspect, the dynamic mirror assembly of the present invention includes a controller capable of automatically placing the dynamic mirror assembly in an intermediate state between the dark state and the light state according to manual input or based on one or more of a clock, a light sensor, or a GPS signal.

In one aspect, the switching material switches states in at least one direction due to a photochromic reaction and switches in another direction due to thermal inversion, and the threshold temperature is above a conventional operating temperature range of the dynamic mirror. In another aspect, the dynamic mirror assembly of the present invention can further include a heating element that drives the switching material in another direction due to the thermal reaction that occurs.

In yet another aspect, the switching material includes a chromophore that darkens due to a photochromic reaction and lightens due to thermal reversals that occur above the threshold temperature. In a further aspect, the threshold temperature is greater than 60 ℃, or greater than 70 ℃, or greater than 80 ℃, or greater than 90 ℃.

When we say that the dynamic mirror assembly of the present invention has a switching material that includes a dark state and a bright state, we refer to two opposing states, the dark state being a state in which the amount of light transmitted is lower than that transmitted in the bright state. A relative intermediate state between the bright state and the dark state is possible and desirable, and each intermediate state will be understood to be brighter or darker than the other. Because the switching material is placed between the mirror and the viewer, the dark state will cause the component to reflect less light from the mirror than the light state.

When we refer to a photochromic reaction we refer to a reaction that lightens or darkens a material when exposed to light, thereby affecting the dark or bright state of the material. When we refer to an electrochromic reaction we refer to a reaction that lightens or darkens a material when exposed to an electric current, thereby affecting the dark or bright state of the material. When we refer to thermal inversion above a threshold temperature we refer to inversion to a thermodynamically more stable state above the threshold temperature that serves to lighten or darken the material when exposed to temperatures above the threshold temperature, thereby affecting the dark or bright state of the material. When we say that a switching material having a dark state and a bright state switches states in one direction or the other, we mean that it changes from a bright state to a dark state or vice versa, as opposed to the previous.

A switching material will be understood to generally comprise at least one chromophore and may comprise more than one chromophore. For example, the chromophore may be a bistable P-type chromophore, meaning that once the chromophore is in a dark state, it will remain in that state until subjected to a stimulus to transition them away from that state. Examples of possible stimuli that may be used to transition the chromophore from one state to another include light of the appropriate wavelength, power of the appropriate voltage, or the amount of heat required to raise the system temperature above a threshold temperature for thermal reversal.

The present invention provides, in part, a vehicle mirror comprising a photochromic switching material that darkens when subjected to a light source in response to the light source, thereby minimizing transmission of light to a vehicle operator.

The mirror can operate in two modes: the first "night mode" will ensure that the mirror reflects a lower percentage of incident light to reduce any glare to the vehicle operator that may be associated with any following vehicle. The second "daytime mode" will allow the mirror to reflect a higher percentage of incident light.

An optional third mode would include aspects of the first and second modes in that it can darken or lighten rapidly in response to changing circumstances (e.g., introducing a need for low transmission, such as entering a tunnel while driving during the day).

In another aspect, the vehicle mirror may be self-dimming or self-brightening in that the control mechanism will automatically respond to changes in ambient light conditions.

In another aspect, the self-dimming mirror is capable of achieving an intermediate state between a daytime mode and a nighttime mode. The intermediate state may be set by the user or based on the light sensor and the time of day.

In another aspect, the self-dimming mirror may include an automatic reset from "night mode" to "daytime mode" when the vehicle is parked at night or when the driver enters the vehicle during the daytime.

In another aspect, the self-dimming mechanism of the mirror can be implemented using a Light Emitting Diode (LED) light source. The light source may comprise an LED emitting a range of wavelengths, for example less than 300nm, between 300-700nm or more than 700nm or a combination of the above. In a related aspect, one wavelength range may be used to drive the photochromic material of the mirror to a darkened state, while another wavelength range may be used to lighten the material.

In another related aspect, the photochromic material can also be electrochromic, and one reaction (e.g., a photochromic mechanism) can be used to darken the material, while another reaction (e.g., an electrochromic mechanism) can be used to lighten the material. The photochromic mechanism can be implemented by subjecting the material to an LED light source, while the electrochromic mechanism can be induced by applying a voltage.

In another aspect, the photochromic material may transition from a dark state/low reflectivity state to a light state/high reflectivity state above a particular temperature threshold, wherein the photochromic mechanism may be used to darken the material and the thermo-lightening mechanism may be used to lighten the material. The thermo-brightening reaction will occur above a threshold temperature that is higher than the normal operating temperature range of the mirror. Referring to FIG. 1, an example of a rearview mirror is shown as a disassembled assembly 100. The mirror may be, for example, a rear view mirror or a side view mirror in a vehicle. In this example, the mirror is photochromic; darkening in response to light of one wavelength range and brightening in response to light of a second wavelength range. The back plate 101 is used to attach the photochromic lens assembly to the mechanical portion of the existing lens system that allows for mounting to the vehicle and for sighting of the lens. A light emitting diode ("LED") light array 103 is bonded to the back plate or mechanically attached.

The light emitting diode ("LED") lamp array 103 may be a light guide plate with side-lit LEDs. It may have a reflective backing to direct more light from the LED to the adhesive layer 105. For example, it may be glass, or plastic or silicone, especially liquid injection molded silicone. Ideally, it has a high transmittance in the UV range. It may have a light diffuser on the side near the adhesive layer 105. Ideally, it should withstand exposure to UV light. An optional filter that blocks visible light may be provided that is configured between the LEDs and the light guide plate to filter out low levels of visible light (penetrating the visible region) emitted by the uv LEDs. Further, a filter may optionally be arranged between the LED array 103 and the mirror 104.

The mirror 104 is attached to the LED array 103. The mirror 104 should have a high reflectivity in the visible region of the electromagnetic spectrum and a high transmissivity in the UV region of the electromagnetic spectrum. Mirror 104 may be a half-silvered mirror formed by sputtering gold, chromium, aluminum, or silver onto a glass or transparent surface or laminating a polyethylene terephthalate ("PET") film. Mirror 104 may also be a multilayer dielectric coating with alternating layers of high refractive index material and low refractive index material of specified layer thicknesses to achieve the indicated reflective and transmissive properties. Other mirrors known in the art are possible. The mirror 104 may be curved to form a concave or convex surface. An optional resistive heating element 102 may be adhered between the back plate 101 and the LED lamp array 103 or between the LED lamp array 103 and the glass 104. The adhesive layer 105 includes a switching material that may contain one or more photochromic dyes and is bonded to the outer layer 106.

Layer 105 may include one or more layers of polyvinyl butyral ("PVB"), poly (ethylene-vinyl acetate) ("PEVA" or "EVA"), pressure sensitive adhesive ("PSA"), or any combination of the above. In one example, the adhesive layer is divided into two parts, a first interior portion comprising a photochromic dye and a second exterior portion comprising a UV absorbing material or UV absorber ("UVA"). Layer 105 may also be an adhesive stack formed by laminating a dye-containing PET film between two adhesive layers. The outer layer of such an adhesive stack may comprise UVA. The outer layer 106 is bonded to the 105 layer and may be composed of glass or plastic. The outer layer 106 may be text marked or etched or may have a pattern to mask functional elements of the embodiment, such as an edge seal. In another example, the outer layer 106 is preferably composed of glass, which may be curved to form a concave or convex mirror, or not curved. The outer layer 106 may also include a coating on the inner or outer surface. The coating may include a UV absorber that can block 99.5% or more of the UV light source. These coatings may be adhered to either surface of the outer layer 106 by sputtering, or they may be flow coated in an organic matrix. Any UV absorber in

layers

105 or 106 will absorb UV (and/or high energy visible light) that causes a photochromic darkening reaction in some photochromic dyes.

In one embodiment, the layer 105 may comprise a layer-by-layer coating comprising a dye-containing layer applied to a polymeric substrate (such as PET), such as disclosed and claimed in U.S. patent No. 9, 453,949, the disclosure of which is incorporated herein by reference. In this aspect, a layer-by-layer coating may be used that includes a polymeric substrate and a composite coating that includes a first layer and a second layer. Typically, the first layer is immediately adjacent to the polymeric substrate at a first face thereof and the second layer is immediately adjacent to the first layer at an opposite face thereof. The first layer includes a polyionic binder and the second layer includes a dye. Each layer includes a binder group component, wherein the binder group component of the first layer and the binder group component of the second layer form a complementary binder group pair.

As used herein, the phrase "complementary binding group pair" means that a binding interaction (such as electrostatic binding, hydrogen bonding, van der waals interactions, hydrophobic interactions, and/or chemically induced covalent bonding) exists between the binding group component of the first layer and the binding group component of the second layer of the composite coating. A "binding group component" is a chemical function that synergistically establishes one or more of the binding interactions described above with a complementary binding group component. These components are complementary in the sense that the binding interactions are created by their respective charges.

Typically, these layer-by-layer coatings include a plurality of these composite coatings. The number of layers of the composite coating is not intended to limit in any way the number of possible composite coatings, and one of ordinary skill will understand that this description is merely exemplary and illustrates embodiments having multiple or multiple composite coatings.

In one example, the side view mirror uses sunlight to transition to a brighter (higher reflectance) state for "daytime mode" and uses UV light from the LED lamp array 103 to transition to a darker (lower reflectance) state for "nighttime mode" mode. In the eye condition, the filtered sunlight will drive the photochromic reaction in layer 105, which causes the photochromic layer to transition to a bright state. In such a scenario, the UV component of the sunlight is filtered and the photochromic layer is exposed to only lower energy visible light, which results in a photochromic brightening of the active layer. The daytime mode may be triggered simply by the presence of sunlight. In low light or high glare conditions, the uv LEDs in the LED array 103 may be turned on to activate or dim the photochromic layer, thereby transitioning the mirror to a low reflection state for night mode operation.

The mirror 104 allows the transmission of UV backlight from the LED array 103 to the photochromic switching material in the layer 105. This achieves darkening of the photochromic layer and reflects the visible light component of the light transmitted through the outer layer 106, thus acting as a mirror. The switching speed of the photochromic material can be fast; for example, its half-life may be in the range of minutes, or even seconds. The outer layer 106 with UV cut-off function may protect the user from exposure to UV from the LED array 103 and also serve the dual purpose of preventing the mirror from darkening during the day. Those skilled in the art will appreciate that many commercial uv leds have a light emission profile such that low levels of visible light (penetration into the visible region) can be emitted. To prevent the consumer from seeing this light, the mirror 104 may be provided with a filter that blocks the transmission of visible light. One commercial example of such a filter is UG11 from schottky. Night mode may be provided by a separate clock Or automatically triggered by a clock in combination with a GPS for indicating the vehicle's position, which may be triggered by the user, or which may be triggered by a sensor reading. Once the UV backlight is turned off, the low reflection state in this example may continue until daytime, at which time exposure to sunlight may cause a photochromic brightening reaction that returns the mirror to the high reflection state. The photochromic layer can comprise one or more chromophores. The

elements

106, 105 and 104 may be laminated together to provide a mirror laminate with high structural integrity that allows for the use of thinner, e.g., chemically treated, glass (e.g., from

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Glass or dragontril from AGC ^TM Glass) or plastic layer for reducing the weight of the mirror assembly and providing NVH advantages. Chemically treated glass is known in the art to be stronger and lighter, allowing for the use of thinner panes or panels.

Referring to fig. 2, a second example is generally shown as a decomposition component 200. However, the LED array 103 in fig. 1 is composed of only one type of LED lamp (UV lamp for darkening the photochromic layer 105), and the LED lamp array 203 in fig. 2 is composed of two types of LED lamps. The first type of LED emits one wavelength range suitable for darkening the photochromic layer 205 and the second type of LED emits a second, different wavelength range suitable for brightening the photochromic layer 205. In one example, the LED lamp array 203 includes LEDs that emit light in the wavelength range of 350-410nm to darken the photochromic layer 205, and LEDs that emit light in the wavelength range of 450-800nm to lighten the photochromic layer 205. Alternatively, the LED array may also be located at one side of the mirror, with a diffuser or light guide guiding the light to the photochromic layer. Thus, the element 203 may be a light guide plate with side-lit LEDs. It may have a reflective backing to direct more light from the LED to the photochromic layer 205. It may be glass, or plastic or silicone, in particular liquid injection molded silicone. Ideally, it has a high transmittance in the UV range. It may have a light diffuser on the side near 205. Ideally, it should withstand exposure to UV light and visible light. There may be a filter blocking visible light that is configured between the LEDs and the light guide plate to filter out low levels of visible light (penetrating the visible region) emitted by the uv LEDs, but allows light of a wavelength corresponding to the second LED in the array 203. Further, a filter may optionally be arranged between the LED array 203 and the mirror 204.

Array 203 is bonded to back plate 101 or mechanically attached. The mirror 204 is attached to or near the LED array 203. The mirror 204 should have a high transmittance in the UV region of the electromagnetic spectrum, a high reflectance in a large part of the visible light region of the electromagnetic spectrum, and a high transmittance of visible light at a specific wavelength corresponding to the visible light LEDs on the LED array 203. The mirror 204 may be curved to form a concave or convex surface. Further, the mirror 204 may have a polarizing coating or film that may be attached using a transparent PSA. The outer layer 206 is bonded to the layer 205 and is composed of glass or plastic. The outer layer 206 may be text marked or etched or may be patterned to mask example functional elements such as edge seals. In another example, the outer layer 206 is composed of glass that is bent to form a concave mirror or a convex mirror. The outer layer 206 may include a coating on the inner or outer surface. The coating may include 99.5% or more UVA that can block the UV light source. These coatings may be adhered to either surface of the outer layer 206 by sputtering, flow coating an organic substrate, or other deposition techniques known in the art. The outer layer 206 may also include a polarizing filter that is coated or attached to one face of the layer 206 using a plastic film and PSA. The polarizing filter of layer 206 must be vertically aligned with the polarizing coating or film of mirror 204.

The example described with reference to fig. 2 operates using an active lightening function (visible light LEDs) instead of passive lightening (filtered sunlight). This means that no sunlight is required to lighten the mirror to restore it to daytime mode. Even at night, the mirror can be switched to provide higher reflectivity. As with the previous examples, the mirror may also operate in a daytime mode and a nighttime mode, either of which is automatically controlled based on time and/or GPS, or based on sensor inputs, or based on some other feedback. The mirror may also be manually controlled based on user interaction.

In an example of automatic operation, detection of a bright ambient lighting condition (e.g., gaze) may cause visible light LEDs in LED array 203 to be turned on, thereby brightening photochromic layer 205 and achieving a high reflectivity state. With visible light LEDs, when light from the visible light LED passes through mirror 204 and its associated linear polarizer to reach photochromic layer 205, a brightening of the photochromic layer occurs, triggering a photochemical brightening reaction to achieve a high reflectivity state. Any remaining polarized visible light transmitted through the photochromic layer is blocked by a linear polarizer on or attached to the outer layer 206. Since the linear polarizer on or attached to the outer layer 206 is a crossed polarizer relative to the linear polarizer on 204, no UV escapes from the front of the mirror, thereby protecting the user from the LED light. In one aspect, layer 205 may comprise a layer-by-layer coating as described above, comprising a dye-containing layer applied to a polymeric substrate such as PET.

Also, when the vehicle light sensor detects a low ambient light condition (e.g., night or tunnel), the uv led is activated, darkening the photochromic layer to achieve a low reflectivity state. The cross polarizers and/or optional UV absorbers in layer 205 may prevent light from the UV LEDs in LED array 203 from escaping the side view mirror assembly in the same manner as described above for visible light LEDs. Thus, the element 203 may be a light guide plate with side-lit LEDs, as already described. Any light (UV or visible light) from the LED array 203 will not or only very little light will be emitted from the side view mirror assembly. The UV filter on the outer glass layer 206 also ensures that the photochromic layer 205 does not darken accidentally from sunlight. The mirror 204 reflects incident sunlight, providing a mirror function for both high and low reflectivity states. Additional light filtering strategies for ensuring that no light can leave the mirror assembly are possible. For example, a pair of orthogonal polarizers may be replaced by two circular polarizers, with the first being the right circular polarizer and the second being the left circular polarizer. In a second example, a pair of crossed polarizers may be replaced by a single notch filter on the outer glass, chosen The notch filter is selected such that the wavelength of light generated by the visible LED backlight is concentrated in the reflection band of the notch filter. In a third example, the crossed polarizers may be replaced with a light guiding layer between the LED array 203 and the mirror 204 to minimize light exiting the mirror assembly in the direction of the driver or vehicle occupant, one commercially available example of such a light guiding layer is from 3M ^TM ALCF-a2+.

Elements

206, 205, and 204 may be laminated together to provide a mirror laminate with high structural integrity that allows for the use of thinner glass, such as chemically treated glass (e.g., from

Is->

Referring to fig. 3, a third example is generally shown as a decomposition component 300. An outer layer 306, consisting of glass or plastic, is bonded to layer 305. Layer 305 includes a photochromic material. In one aspect, layer 305 may comprise a layer-by-layer coating as described above that includes a dye-containing layer applied to a polymeric substrate such as PET. In this example, the outer layer 306 includes a notch filter to block narrowband light. These notch filters may be absorptive or dichroic filters, such as applied as a coating on the outer layer 306 or adhered to the outer layer 306 using a transparent PSA. The absorptive notch filter may also use a layered adhesive layer in which a dye is present that absorbs light from the second array of visible light LEDs. Notch filters may be used in place of the polarizing layers to allow visible light to enter and exit the mirror, but block specific wavelengths emitted by the LEDs on the LED array 303. LED array 303 may include colored LEDs that emit in the wavelength range of 450-800 nm. For example, if the LED emits light at a wavelength of 650nm, the notch filter on the outer layer 306 may be selected so as to allow all visible wavelengths to pass through, but block 650nm and just at that peak Wavelengths around the value, thereby preventing escape of light from 650nm leds. The outer layer 306 may also be text marked or etched or may be included to mask exemplary functional elements, such as edge seals. In one example, the outer layer 306 is preferably composed of glass that is bent to form a concave or convex mirror, particularly a rear or side view mirror of a vehicle. The outer layer 306 may include a coating on the inner or outer surface. The coating may include a UV absorber that can block 99.5% or more of the UV light source. These coatings may be adhered to either surface of the outer layer 306 by sputtering, flow coating with an organic matrix, or other deposition techniques known in the art. The mirror 304 should have a high transmittance in the UV region of the electromagnetic spectrum, a high reflectance in a large portion of the visible region of the electromagnetic spectrum, and a high transmittance of visible light at a specific wavelength corresponding to the visible LEDs on the LED array 303. The

elements

306, 305 and 304 may be laminated together to provide a mirror laminate with high structural integrity that allows for the use of thinner glass, such as chemically treated glass (e.g., from

Is->

Referring to fig. 4, a fourth example is generally shown as a decomposition component 400. Adhesive layer 405 may comprise a PVB or EVA encapsulant film, and the film may comprise a mixed photochromic-electrochromic dye. For photochromic-electrochromic switching materials, one transition (from light to dark or from dark to light) occurs in response to light and the other transition in the opposite direction occurs in response to electricity. The dye may be contained in a polymer gel matrix, collectively referred to herein as a "switching material," and the switching material may be sandwiched within a stack of two Transparent Conductive Electrodes (TCEs). TCE may comprise a thin coating of conductive material, such as ITO, gold, etc., on the inner surface of the sandwich structure, adjacent to the dye-containing polymer gel. An example of such a membrane can be found in US 9588358.

The photochromic-electrochromic example of fig. 4 may operate in an automatically triggered daytime mode and a nighttime mode, or it may operate dynamically based on sensor input. When the on-board light sensor detects a bright ambient lighting condition (e.g., gaze), a voltage is applied to the adhesive layer 405, which causes the layer to lighten and reach a high reflectivity state when sunlight is reflected from the mirror 304. The UVLEDs of the LED layer 303 will be activated when the vehicle-mounted light sensor detects a low ambient light condition (e.g., at night or when the vehicle is in a tunnel). UV light from the LED array 303 passes through the mirror 304, darkening the photochromic-electrochromic layer to achieve a low reflectivity state. The UV cut-off filter on the outer glass layer 406 can prevent light from exiting the side view mirror assembly, protecting the consumer and also ensuring that no unintended darkening of the photochromic layer occurs due to sunlight.

A heating element may be included in the rear view mirror to prevent fogging and icing of the mirror. The heating element 102 may be located between the back plate 101 shown in fig. 1-4 and any of the LED arrays (i.e. 103, 203, 303) described in the previous examples, or between the LED arrays (103, 203, 303) and any of the mirrors (i.e. 104, 204, 304) described in the previous examples. If the heating element 102 is located between the LED array and the mirror, it may be composed of a transparent thin wire or a TCE type heater that is substantially transparent to the UV wavelengths and wavelengths of light that will lighten the photochromic layers (105, 205, 305, 405).

Referring to fig. 5, a fifth example of a mirror in accordance with the present invention is generally shown as an exploded assembly 500. The LED array 503 in fig. 5 may include: one type of LED lamp (as in fig. 1), wherein the LED array 103 comprises uv LEDs for darkening the photochromic layer 105; or two types of LEDs (as in fig. 2), wherein the LED lamp array 203 includes LEDs that emit light having a wavelength in the range of 350-410nm to darken the photochromic layer 205, and LEDs that emit light having a wavelength in the range of 450-800nm for brightening the photochromic layer 205.

The array 503 is bonded to the assembly or mechanically attached. A mirror 504 is attached to the LED array 503. In one example, the mirror 504 has high transmittance in the UV region of the electromagnetic spectrum, high reflectance in a majority of the visible region of the electromagnetic spectrum, and may also have high transmittance of visible light at a particular wavelength corresponding to the visible LEDs on the LED array 503. Mirror 504 may be curved to form a concave or convex surface. Further, the mirror 504 may have a polarizing coating or film that may be attached using a transparent PSA. The outer layer 506 is bonded to the layer 505 and is composed of glass or plastic. The outer layer 506 may be text marked or etched or may be patterned to mask exemplary functional elements, such as edge seals. In another example, the outer layer 506 is composed of glass that is bent to form a concave mirror or a convex mirror. The outer layer 506 may include a coating on the inner or outer surface. The coating may include 99.5% or more UVA that can block the UV light source. These coatings may be adhered to either surface of the outer layer 506 by sputtering, flow coating with an organic matrix, or other deposition techniques known in the art. The outer layer 506 may also include a polarizing filter that is coated or attached to one face of the layer 506 using a plastic film and PSA. The polarizing filter of layer 506 must be vertically aligned with the polarizing coating or film of mirror 504.

In an alternative example, the mirror comprises an LED array 507 at one side of the stack, which emits light with a wavelength in the range of 450-800nm to lighten the photochromic layer 505. This may replace the LED assembly 503 or supplement the LED assembly 503. The entire mirror assembly is enclosed in a housing 508. In another alternative example, an LED or other light source 509 that emits light having a wavelength in the range of 450-800nm to lighten the photochromic layer 505 is adhered to the housing. In the case of a side view mirror, the light source 509 may be directed in such a way that the reflected light is not visible to the driver.

The example described herein with reference to fig. 5 operates using an active lightening function (visible light LEDs) rather than passive lightening (filtered sunlight). This means that no sunlight is required to lighten the mirror to restore it to daytime mode. Even at night, the mirror can be switched to provide higher reflectivity. As with the previous examples, the mirror may also operate in a daytime mode and a nighttime mode, either of which is automatically controlled based on time and/or GPS, or based on sensor input, or based on some other feedback. The mirror may also be manually controlled based on user interaction.

In an example of automatic operation, detection of a bright ambient lighting condition (e.g., gaze) may cause the visible light LEDs in LED array 503 and/or LED array 507 and/or lamp array 509 to be turned on, thereby brightening the photochromic layer 505 and achieving a high reflectivity state. With visible light LEDs, when light from the visible light LED passes through mirror 504 and its associated linear polarizer to reach the photochromic layer 505, a brightening of the photochromic layer occurs, triggering a photochemical brightening reaction to achieve a high reflectivity state. Any remaining polarized visible light transmitted through the photochromic layer is blocked by a linear polarizer on or attached to the outer layer 506. Since the linear polarizer on or attached to the outer layer 506 is a crossed polarizer relative to the linear polarizer on the mirror 504, little or no UV light escapes from the front of the mirror, thereby protecting the user from the LED light.

Also, when the vehicle light sensor detects a low ambient light condition (e.g., night or tunnel), the uv led is activated, darkening the photochromic layer to achieve a low reflectivity state. The cross polarizers and/or optional UV absorbers in layer 505 may prevent light from the UV LEDs in LED array 503 from escaping the side view mirror assembly in the same manner as described above for visible light LEDs. No light (UV or visible light) from the LED array 503 will be emitted from the side view mirror assembly or only a very small amount of light will be emitted. The UV filter on the outer glass layer 506 also ensures that the photochromic layer 505 does not darken accidentally from sunlight. Mirror 504 reflects incident sunlight, providing a mirror function for both high and low reflectivity states. Additional light filtering strategies for ensuring that no light can leave the mirror assembly are possible. For example, a pair of orthogonal polarizers may be replaced by two circular polarizers, where, for example, the first polarizer is a right circular polarizer and the second polarizer is a left circular polarizer. In a second example, a pair of crossed polarizers may be replaced by a single notch filter on the outer glass, the notch filter being selectedSo that the wavelength of light generated by the visible LED backlight is concentrated in the reflection band of the notch filter. In a third example, the crossed polarizers may be replaced with a light guiding layer between the LED array 503 and the mirror 504 to minimize light exiting the mirror assembly in the direction of the driver or vehicle occupant, one commercially available example of such a light guiding layer is from 3M ^TM ALCF-a2+. In another example, only directional LED509 is used to transition from "night mode" to "daytime mode" and no polarizer is used in layer 505 and no polarizer or light guiding layer is employed between LED array 503 and mirror 504. This is possible because this light is not directional and because it is reflected away from the driver, it is not seen during the brightening.

In another example of automatic operation in the example of fig. 1, the mirror assembly may use GPS and time or sensor technology to dim to "night mode" and remain in "night mode" while driving (or the sun re-lightens it). However, a sensor may be used to ensure that the mirror automatically resets to "daytime mode", either when the vehicle is stopped and ignition is removed or when the vehicle is entered. In this mode, no polarizer is used in layer 505 and no polarizer or light guiding layer is required between LED array 503 and mirror 504. Light from

LED arrays

503, 507 or 509 is used to transition from night mode to daytime mode.

In all of the examples described above, the mirror can also be controlled to an intermediate state between the dark state and the low state. Such control may be achieved manually by a user selecting a desired reflectivity, or it may be automatically controlled based on sensor input to set the mirror in an optimal reflectivity state between a fully dark state and a fully bright state. The control system may also include algorithms to ensure that the minimum reflectivity level required by law is reached during daytime operation.

In an alternative example, the photochromic layer includes a chromophore that switches from light to dark based on a photochromic reaction and may also switch from dark to light due to a thermo-dependent light reaction that occurs at a temperature above a threshold temperature that is higher than would be reached during normal operation and higher than would be reached when the mirror defroster is turned on. In an example, the chromophore may gradually change from a dark to a light state when the chromophore is heated above a threshold temperature of 60 ℃ or above a threshold temperature of 70 ℃ or above a threshold temperature of 80 ℃ or above a threshold temperature of 90 ℃. In this example, the resistive heating element 102 may also be used to transition the photochromic layer back to the lit state through a thermo-brightening reaction. This may be advantageous because no LEDs are required for one of the switching directions and also to simplify the required filters. In the normal operating temperature range of the mirror (e.g., -20 ℃ to 50 ℃, or-30 ℃ to 60 ℃, or-40 ℃ to 70 ℃), the chromophore remains thermally stable such that the chromophore will remain in a dark state without the need to continuously apply UV light as in some prior art examples. Furthermore, the dark and bright states change little or no at all over the normal operating temperature range; that is, the bright and dark states are independent of temperature over the normal operating temperature range of the mirror.

Fig. 6a shows an example of a photochromic lens constructed and tested in accordance with the present invention, shown as an exploded lens box housing 600. A proof of concept prototype mirror was developed from the example shown in fig. 1 and its corresponding description. In this example, the backplate 101 and heating element 102 from fig. 1 are excluded from the prototype construction. Fig. 6a shows a general exploded view of a prototype mirror design. The LED backlight array 603 was constructed by fixing two 365nm LEDs (SST-10-UV-A130-E365-00 from Luminous devices) with 875mW radiant flux to the back plate. Electrical contacts are soldered to the LED array 603, fastened to the mirror box housing 601, connected to a power source (not shown) and the housing is covered with a cover plate 602.

Fig. 6b shows the various layers included in the mirror stack 604. The photochromic layer 606 was gap coated to the mirror 605 (5 mm thick Mirropane from Pilkington, NSG) by using an 8mil fixed gap coating bar ^TM ) Manufactured above, the solution comprised 1.8wt% of the photochromic chromophore group shown in figure 6c, 20wt% of PVB resin from Kuraray Corporation and rhodosolviris solvent from Solvay. The rhodosolv IRIS solvent would be allowed to evaporate, leaving a solid film. The mirror stack 604 also includes a layer of PVB 607

Natural UV PVB), followed by a second layer PVB 608, comprising a UV cut-off wavelength of 400nm (/ -)>

Extra Protect PVB) followed by a 2.1mm thick clear float glass 609. Additional PVB layers are used in this example to provide more effective UV blocking for higher wavelengths. The mirror stack 604 was then laminated together using a vacuum bag process that included subjecting the vacuum bag to a vacuum of-735 mmHg, heating the vacuum bag to 55 ℃ for 10 minutes, then ramping the temperature to 135 ℃ over 15 minutes, holding the temperature for 30 minutes, and finally cooling the vacuum bag to 60 ℃ over 10 minutes. The laminated mirror stack 604 is connected to the mirror box housing 600 and successfully toggles between a high reflectivity state (about 43% reflectivity) and a low reflectivity state (about 2% reflectivity). By activating the 365nm LED, the mirror stack 604 transitions to 90% of the fully darkened state in about two minutes. Exposed to an intensity of about 100W/m ² The mirror stack 604 will switch back to the bright state in about 15 minutes.

In another example, a photochromic lens was constructed and tested according to the present invention. Fig. 6a again shows a general exploded view of the prototype mirror design. The LED backlight array 603 was constructed by fixing two 365nm LEDs (SST-10-UV-A130-E365-00 from Luminous devices) with 875mW radiant flux to the back plate. Electrical contacts are soldered to the LED array 603, fastened to the mirror box housing 601, connected to a power source (not shown) and the housing is covered with a cover plate 602. Fig. 6b shows the various layers included in the mirror stack 604. In this example, the photochromic layer 606 was gap coated to the mirror 605 (5 mm thick Mirropane from Pilkington, NSG) by using an 8mil fixed gap coating bar ^TM ) Manufactured above, the solution comprised 3.6wt% of the photochromic chromophore group shown in figure 6d, 20wt% of PVB resin from Kuraray Corporation and rhodosolv IRIS solvent. The rhodosolv IRIS solvent would be allowed to evaporate, leaving a solid film. The mirror stack 604 also includes a layer of PVB 607

Extra Protect PVB) followed by a 2.1mm thick clear float glass 609. The mirror stack 604 was then laminated together using a vacuum bag process that included subjecting the vacuum bag to a vacuum of-735 mmHg, heating the vacuum bag to 55 ℃ for 10 minutes, then ramping the temperature to 135 ℃ over 15 minutes, holding the temperature for 30 minutes, and finally cooling the vacuum bag to 60 ℃ over 10 minutes. The laminated mirror stack 604 is connected to the mirror box housing 600 and successfully toggles between a high reflectivity state (about 50% reflectivity) and a low reflectivity state (about 6% reflectivity). By activating the 365nmLED, the mirror stack 604 transitions to 90% of the fully darkened state in about two minutes. Exposed to an intensity of about 200W/m ² The mirror stack 604 will switch back to the bright state in about 30 seconds.

Those skilled in the art will appreciate that the percent reflectivity of the mirror stack 604 will be a function of the reflectivity of the mirror 605 and PVB adhesive layers (607 and 608) utilized, the transmissivity of the float glass 609, the chromophore type (e.g., the type shown in fig. 6c and 6 d), and the loading selected. Those skilled in the art will further appreciate that the transition time is a function of chromophore structure, the substrate in which the chromophore resides, and the intensity of the light.

Examples of photochromic and photochromic-electrochromic switching materials

Photochromic and photochromic-electrochromic materials can be used to provide switching functionality in the rearview and side view mirrors of the present invention. Photochromic and photochromic-electrochromic chromophores or dyes absorb visible light in one state (dark state) and allow visible light to pass in another state (light state). The term "chromophore" or "dye" refers to these light absorbing materials and the terms are used interchangeably. Examples of photochromic chromophores suitable for use in the present invention darken (i.e., change to a light absorption mode) in response to light of one wavelength range and lighten (i.e., change to a light transmission mode) in response to light of a different wavelength range.

For example, suitable chromophores may darken in response to light in the range of 350-410 nm and lighten in response to light in the range of 450-800 nm. Exemplary chromophores for use in accordance with the present invention described below are P-type photochromic materials, meaning that they are bistable. P-type photochromic materials are discussed in pureappl. Chem, vol.73, no.4, pp.639-665, 2001; they are familiar to those skilled in the art of photochromism. Once the photochromic chromophore is in the dark state, it will remain in that state until stimulated to transition it away from that state. Examples of possible stimuli that may be used to transition the chromophore from one state to another include light of an appropriate wavelength, power of an appropriate voltage, or the amount of heat required to raise the system temperature above a threshold temperature. This function has the potential advantage that less power is required to maintain the mirror in a particular state (bright or dark state) over a wider operating temperature range. For example, the photochromic materials described below will continue to be in a dark state or a light state at an operating temperature ranging from-20 ℃ to 50 ℃, or ranging from-30 ℃ to 60 ℃, or ranging from-40 ℃ to 70, or at least-40 ℃, or at least-30 ℃, or at least-20 ℃, up to about 90 ℃, or up to 85 ℃, or up to 80 ℃, or up to 75 ℃.

In contrast, T-type photochromic materials (such as those cited in prior art US 5373392) will thermally reverse from a dark state to a light state at lower temperatures. For example, they will switch at temperatures below 70 ℃, or below 60 ℃, or below 50 ℃, or below 40 ℃ or below 30 ℃, without continuous exposure to UV light. For photochromic materials including T-type photochromic compounds, the uv led must remain on for the entire time that the night mode is required, which results in significantly higher power consumption, increased generation of heat that must be dissipated from the mirror assembly, and higher requirements for protection against photochemical degradation.

In other examples, suitable chromophores are photochromic and electrochromic, meaning that one of the transitions (from a dark state to a light state or vice versa) is driven by light and the opposite transition is driven by electricity. For example, the photochromic-electrochromic chromophore darkens in response to UV and visible light in the range of 350-410nm and lightens when a voltage is applied across the switching material through a transparent conductive electrode in contact with the switching material. These photochromic-electrochromic chromophores are also P-type photochromic materials and will also provide a significant improvement over the T-type photochromic chromophores used in eyeglasses and in the prior art examples of rearview mirrors that rely on thermal reverse reactions to drive the chromophores into a bright state.

Chromophores suitable for use with the examples shown in fig. 1, 2 or 3 include classes of compounds from the triene family (e.g., diarylethenes, dithienylcyclopentenes, and sulfides) that are photochromic, meaning that they interconvert between colorless or nearly colorless open-loop structures and colored closed-loop structures under photochemical conditions. Upon absorption of light having a wavelength of less than 450nm and more preferably less than 400nm, the chromophore undergoes an electrical ring closure reaction to produce a dark state isomer. Upon absorption of light having a wavelength between 450-800nm, the chromophore undergoes an electrical ring-opening reaction to produce the bright state isomer.

Examples of such chromophores are outlined in US 7777055. The material may darken (e.g., to a 'dark state' or "photodarkening") when exposed to Ultraviolet (UV) light or light including wavelengths of about 350nm to about 450nm, and it may lighten ("fade", "photobleach", "photobleaching", or achieve a "bright state") when exposed to light including wavelengths of about 450nm to about 800 nm. Preferably, the chromophore fades when exposed to sunlight that has passed through a cutoff filter that filters out light that includes wavelengths shorter than 450nm ("450 nm cutoff filter") or shorter than 420nm ("420 nm cutoff filter") or shorter than 410nm ("410 nm cutoff filter") or shorter than 400nm ("400 nm cutoff filter"). These chromophores may have the additional structural feature that they undergo a thermal ring-opening reaction above a threshold temperature. These chromophores are classified as P-type photochromic materials because this property differs from the T-type photochromic behavior defined above because the P-type chromophores do not undergo a thermal ring-opening reaction below a threshold temperature. At temperatures at or above the threshold temperature, the P-type chromophore undergoes a rapid thermal ring-opening reaction. The switching material may be optically transparent, or substantially transparent, or not opaque.

A photochromic-electrochromic switching material is used for the example described with reference to fig. 4. The photochromic-electrochromic dye reaction is summarized in formula I. Upon absorption of light having a wavelength less than 450nm, the dye undergoes an electrical ring closure reaction to produce a dark state isomer of the dye. When a voltage is applied to the dye or a light stimulus greater than 450nm is applied, the dye switches back to the bright state isomer.

I is a kind of

Examples of photochromic/electrochromic "switching materials" are outlined in US 10054835. The material may darken (e.g., to a "dark state") when exposed to Ultraviolet (UV) light or blue light from a light source, and may lighten ("fade," to a "bright state") when exposed to a voltage. In some examples, in addition to fading upon application of electrical power, the switching material may fade upon exposure to visible light of a selected wavelength ("photobleaching" ). In some examples, the switching material may darken when exposed to light including wavelengths of about 350nm to about 450nm or any amount or range of wavelengths therebetween, and may lighten when a voltage is applied or when exposed to light including wavelengths from about 450nm to about 800 nm. The switching material may be optically transparent, or substantially transparent, or not opaque.

Electronic device

Fig. 7 shows a schematic diagram of a basic circuit 700 for controlling LEDs for dimming and/or brightening a dynamic mirror. The circuit 700 includes a uv LED703 for darkening the photochromic switching material and a visible LED 704 for brightening the photochromic switching material. However, in some examples, dimming only requires UV LEDs 703, as the lightening reaction is triggered by filtered sunlight (as in the example described with reference to fig. 1), or by electrochromic reactions (as in the example described with reference to fig. 4), or by thermal lightening reactions triggered below a threshold (as described in US5274132 and US 5369158). In these other examples, the visible light LED 704 is not required. In the example described with reference to fig. 2, LED 704 is required to lighten the photochromic material. The brightening LEDs may be of different colors (i.e., different wavelengths or wavelength ranges) depending on the particular photochromic material used. In some examples, they may be LEDs that emit in the Infrared (IR) range. Whether they are used to lighten or dim photochromic materials, LEDs are preferred over other types of light sources (e.g., fluorescent lamps, incandescent lamps, etc.) because of their low power consumption, small form factor, and the ability of LEDs to emit a fairly narrow range of wavelengths. LEDs are also readily available in many different wavelength ranges and, therefore, can be readily matched to the wavelengths required to darken or lighten a particular photochromic material selected for an application.

The voltage source 701 provides the appropriate voltage for powering the LEDs. In this case, the voltage source is described as a DC voltage, but in other examples an AC voltage may be used. In an example, the DC voltage may be 12 volts supplied by a standard vehicle battery, or it may be any other voltage. In the case of both UV and visible LEDs, switch 702 controls whether current flows to one of two possible circuit paths. In one circuit path 705, a voltage is applied across the UV LED 703 for darkening the photochromic film within the mirror. In this case, the UV LEDs 703 are connected in series such that the applied voltage is sufficient to illuminate both LEDs. Different LEDs may have different voltage drops and further voltage regulating circuitry may be provided to provide the correct voltage across each LED.

In the second circuit path 706, a voltage is applied across the visible light LED 704. The LED 704 emits light at a wavelength suitable for brightening a photochromic layer (e.g., 405 in fig. 4) within the assembly (400). The number of LEDs shown in this figure is four. Based on the applied voltage 701, connecting these four LEDs in series will provide the correct voltage drop across each LED to turn them on and run. However, the number of LEDs used for dimming and brightening should be selected to provide the necessary amount of light intensity required to dim and/or brighten the mirror within a set time frame.

Switch 702 may be controlled manually or by an automated process. In one example, the switch may be controlled based on a clock and/or a GPS number to determine whether the mirror should operate in "daytime" or "nighttime" mode. In another example of an automated system, a light sensor may be used to automatically detect the light level and decide whether the mirror should be lit or darkened, and then switch 702 is activated accordingly to turn on UV LED 703 or visible LED 704. It should be noted that switch 702 may also have a third "off" position such that no LEDs are connected. This is the case for mirrors comprising bistable switching materials, which means that once in a certain state (e.g. dark or bright) it does not change further without some external stimulus. Thus, if the mirror is already at the correct transmission level, it can be kept at that transmission level without turning on the LED and without other external stimuli.

As shown in fig. 7, the number of UV LEDs 703 required for darkening may be different from the number of visible LEDs 704 required for brightening the photochromic switching material. The circuit may then be designed to provide the appropriate voltage to operate the LED. Although only a series arrangement of LEDs is shown in this schematic diagram, LEDs may be arranged in a series or parallel configuration, or in a combination of series or parallel configurations, as desired for a particular application.

Fig. 8 is an example of sixteen LEDs arranged on a circuit board. The panel includes eight dimming LEDs (such as 803) and four dimming LEDs (such as 804). The voltage source 701 provides power for driving the LEDs, and the switch 702 selects between a circuit path 805 including a dimmed LED or a circuit path 806 including a dimmed LED. In this example, the voltage applied to the LEDs is variable and can be controlled by the power supply 801. Using the power supply 801 to reduce the applied voltage may be used to turn off or reduce the brightness of the LED, and increasing the applied voltage may be used to increase the brightness of the LED. A dimming LED (such as LED 803) and a brightening LED (such as LED 804) are arranged on the circuit board 807, with some dimming and brightening LEDs arranged in each row to provide more uniform light of each type to the photochromic layer. This results in a more uniform darkening or brightening of the photochromic layer.

Fig. 9a shows a backlight circuit board 900 in which darkened LEDs (such as LED 901) are interspersed with lighten LEDs (such as LED 902). In this example, dimming and brightening LEDs alternate in each row to provide as uniform light as possible to the photochromic switching material. In this example, 16 LEDs are shown, but any number of LEDs and alternating pattern may be used to ensure uniformity of light. In this case, the circuit board is square, but in other examples may be any shape suitable for use within an application. Fig. 9b shows a circuit board 903 having another exemplary configuration of dimming LEDs (such as LED 901) and brightening LEDs (such as LED 902). In this example, dimming and brightening LEDs are arranged in alternating vertical rows, which may provide sufficient light uniformity for dimming and brightening. Dimming and brightening LEDs may also be arranged in horizontal rows on the circuit board 904, as in fig. 9 c. Fig. 9d shows a circuit board 905 having an exemplary arrangement of the example shown in the schematic of fig. 8, with dimmed LEDs partially alternating within and between rows.

Darkened and/or lightened LEDs may also be arranged by using LEDs in combination with a light directing film or filter to create an LED-side configuration, e.g

LED light guide side light type. In this configuration, the LEDs are configured at the edge of the light guiding layer, and the light is fed through the edge of the film or filter and emitted uniformly across the surface of the layer. Light diffusing particles embedded in the light guiding layer suppress total internal reflection, allowing light to exit the sheet via the surface in a controlled and uniform manner. The LEDs may be arranged on one side of the light guiding layer or on both sides or any number of sides of the light guiding layer up to and including each individual side of the light guiding layer. The light guiding layer may be configured with only dimmed LEDs or it may be configured with both dimmed and dimmed LEDs. The dimmed LEDs may be arranged together on the same side of the light guiding layer or they may be distributed between two or more sides of the light guiding layer. Similarly, the brightening LEDs may be arranged together on the same side of the light guiding layerOr they may be distributed between two or more sides of the light guiding layer. The dimming and brightening LEDs may be arranged together on the same side of the light guiding layer, alternating between dimming and brightening LEDs, or as a pattern determined by the relative ratio of dimming LEDs and brightening LEDs required for a particular application, e.g. a repeating pattern of one dimming LED followed by two brightening LEDs. The light guiding layer and associated LEDs may be arranged behind the mirror or in front of the mirror. If the light guiding layer is arranged in front of the mirror, additional design considerations for selecting the light guiding layer may exist, such as low haze and high optical clarity. Those skilled in the art will appreciate that the type of light guiding layer may be selected based on the size of the area to be illuminated and other design considerations. Other LED configurations are also possible.

Fig. 10 shows a general schematic diagram of this basic circuit, showing a voltage source 701, a switch 702 to select between

circuit branches

1002 and 1003, and a dimming LED (such as LED 803) and a brightening LED (such as LED 804). The figure shows that any number of dimmed LEDs and brighter LEDs may be used to suit the application. In this example, the LEDs are shown in a parallel and series configuration, where the LEDs are connected in series and then connected in parallel with other LED strings connected in series. The LEDs may be individual LEDs soldered to the circuit board or they may be LED strips applied to the back plane. A resistor such as 1001 may be used to adjust the voltage drop across the LED to provide the desired voltage. In this case, the resistor is shown as modifying the voltage of the string of illuminated LEDs arranged in parallel. A switching DC-DC converter may be used instead of a resistor to minimize heat loss caused by the current flowing through the resistor. Many other ways of designing this circuit to achieve the desired objective of the switchable mirror are possible and known to those skilled in the art.

Other embodiments

It is contemplated that any embodiment discussed in this specification may be implemented or combined with respect to any other embodiment, method, composition or aspect, and vice versa.

The present invention has been described with respect to one or more embodiments. However, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention as defined in the following claims. Thus, although various embodiments of the invention are disclosed herein, many variations and modifications are possible within the scope of the invention, as would be apparent to one skilled in the art. Such modifications include the substitution of known equivalents for any aspect of the invention in order to achieve the same result in substantially the same way. Numerical ranges include numbers defining the range. When used in conjunction with a value, the terms "approximately" and "about" mean +/-10% of the value. In the specification, the word "comprising" is used as an open term, substantially identical to the phrase "including, but not limited to," but not limited to, and the word "comprising" has a corresponding meaning. As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Citation of a reference herein shall not be construed as an admission that such reference is prior art to the present invention, or any admission as to the content or date of the reference. All publications are herein incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference and was set forth in its entirety herein. The invention includes all embodiments and variants substantially as hereinbefore described and with reference to the examples and drawings.

Directional terms such as "top", "bottom", "upward", "downward", "vertical", "lateral", "interior", "exterior" are used in this disclosure for purposes of providing relative reference only, and are not intended to place any limitations on how any item may be positioned during use, or mounted in an assembly or relative to the environment.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If the definition set forth in this section is contrary to or otherwise inconsistent with the definition set forth in the document incorporated by reference, the definition set forth herein takes precedence over the definition set forth herein by reference.

Claims

1. A dynamic mirror assembly capable of varying the amount of reflected light, comprising:

a. a mirror; and

b. a switching material disposed between the mirror and the viewer, having a dark state and a light state, the switching material switching state in at least one direction due to a photochromic reaction and the switching material switching in the other direction due to one or more of a photochromic reaction or an electrochromic reaction or a thermal reversal above a threshold temperature.

2. The dynamic mirror assembly of claim 1, wherein the switching material switches in the other direction due to a photochromic reaction only.

3. The dynamic mirror assembly of claim 1, wherein the switching material switches in the other direction due to electrochromic reactions only.

4. The dynamic mirror assembly of claim 1, wherein the switching material switches in the other direction due to both a photochromic reaction and an electrochromic reaction.

5. The dynamic mirror assembly of claim 1, wherein the switching material switches in the other direction due to thermal reversals above the threshold temperature.

6. The dynamic mirror assembly of claim 1, wherein said mirror is highly reflective in the visible region and highly transmissive in the ultraviolet region.

7. The dynamic mirror assembly of claim 1, wherein the mirrors are mutual mirrors that appear reflective on one side and transparent on the other side.

8. The dynamic mirror assembly of claim 1, wherein the switching material comprises a chromophore that switches state in at least one direction due to a photochromic reaction and that switches in another direction due to one or more of a photochromic reaction or an electrochromic reaction or a thermal reversal above a threshold temperature.

9. The dynamic mirror assembly of claim 8, wherein the switching material further comprises polyvinyl butyral.

10. The dynamic mirror assembly of claim 1, wherein the mirror comprises one or more of gold, chromium, aluminum, or silver sputtered onto a transparent substrate.

11. The dynamic mirror assembly of claim 1, wherein the mirror comprises a multilayer dielectric material having alternating layers of high refractive index material and low refractive index material.

12. The dynamic mirror assembly of claim 8, wherein the chromophore switches to the dark state via a photochromic reaction when excited by light of one wavelength range and to the bright state via a photochromic reaction when excited by light of a different wavelength range.

13. The dynamic mirror assembly of claim 1, further comprising a light emitting diode on a side of the mirror opposite the switching material, the light emitting diode emitting in a fixed wavelength range to drive one of the state changes.

14. The dynamic mirror assembly of claim 13, wherein the light emitting diode drives the switching material from the bright state to the dark state.

15. The dynamic mirror assembly of claim 13, wherein said fixed wavelength is about 350nm to about 410nm and is used to darken said switching material.

16. The dynamic mirror of claim 13, further comprising an additional light emitting diode that emits light in a wavelength range of 450nm to 800m to lighten the switching material.

17. The dynamic mirror assembly of claim 1, further comprising a filter between the switching material and sunlight such that filtered sunlight transitions the switching material from the dark state to the bright state.

18. The dynamic mirror assembly of claim 13, further comprising a filter between the switching material and sunlight such that filtered sunlight transitions the switching material from the dark state to the bright state.

19. The dynamic mirror assembly of claim 1, wherein the switching material comprises a photochromic-electrochromic material, and wherein the switching material darkens in response to sunlight and lightens in response to electricity.

20. The dynamic mirror assembly of claim 1, wherein the switching material comprises a photochromic-electrochromic material, and wherein the switching material darkens in response to light and lightens in response to electricity.

21. The dynamic mirror assembly of claim 1, wherein the switching material comprises a P-type photochromic material.

22. The dynamic mirror assembly of claim 1, wherein the switching material comprises a photochromic material that photochromically switches to the bright state and to the dark state due to thermal reversals above the threshold temperature.

23. The dynamic mirror assembly of claim 1, wherein the switching material comprises a photochromic material that photochromically switches to the dark state and to the bright state due to thermal reversals above the threshold temperature.

24. The dynamic mirror assembly of claim 1, wherein the threshold temperature is at least 50 ℃.

25. The dynamic mirror assembly of claim 1, wherein the threshold temperature is at least 60 ℃.

26. The dynamic mirror assembly of claim 1, wherein the threshold temperature is at least 70 ℃.

27. The dynamic mirror assembly of claim 1, wherein the dark state of the switching material does not spontaneously revert to the bright state upon removal of a light source in a temperature range of-20 ℃ to 50 ℃, or in a temperature range of-30 ℃ to 60 ℃, or in a temperature range of-40 ℃ to 70 ℃.

28. The dynamic mirror assembly of claim 1, wherein the dynamic mirror assembly has a daytime mode and a nighttime mode, and wherein the dynamic mirror assembly is in a high reflectivity state during the daytime mode and in a low reflectivity state during the nighttime mode.

29. The dynamic mirror assembly of claim 28, comprising a controller that controls whether the dynamic mirror assembly should be in daytime or nighttime mode based on one or more of a clock, a light sensor, or a GPS signal.

30. The dynamic mirror assembly of claim 1, further comprising a controller capable of automatically placing the dynamic mirror assembly in an intermediate state between the dark state and the light state according to manual input or based on one or more of a clock, a light sensor, or a GPS signal.

31. The dynamic mirror assembly of claim 1, wherein the switching material switches state in at least one direction due to a photochromic reaction and switches in the other direction due to thermal reversal, wherein the threshold temperature is above the normal operating temperature range of the dynamic mirror.

32. The dynamic mirror assembly of claim 31, further comprising a heating element that drives said switching material in said other direction as a result of said thermal reversal.

33. The dynamic mirror of claim 1, wherein the switching material comprises a chromophore that darkens due to a photochromic reaction and lightens due to thermal reversals that occur above a certain threshold temperature.

34. The dynamic mirror of claim 1, wherein the threshold temperature is greater than 60 ℃.